Inkjet ink composition containing anti-kogation agents

ABSTRACT

Ink compositions and methods of using the same are disclosed. An example ink composition includes an inkjet vehicle, from about 0.1 wt % to about 10 wt % of colorants, from about 0.01 wt % to about 10 wt % of anti-kogation agents, and from about 0.01 wt % to about 10 wt % of dispersed resin beads.

BACKGROUND

The use of inkjet printing systems has grown dramatically in recentyears, which is attributed to substantial improvements in printresolution and overall print quality coupled with appreciable reductionin cost. Notwithstanding their recent success, intensive research anddevelopment efforts continue toward improving inkjet print quality,while further lowering cost to the consumer.

With inkjet printing, a desired printed image is formed when a precisepattern of dots is ejected from a drop-generating device, known as aprinthead, onto a print medium. The printhead has an array of preciselyformed nozzles located on a nozzle plate and attached to an inkjetprinthead substrate. The inkjet printhead substrate incorporates anarray of firing chambers that receive inkjet ink through fluidcommunication with one or more ink reservoirs. Each firing chamber has aresistor element, known as a firing resistor, located opposite thenozzle so that the inkjet ink collects between the firing resistor andthe nozzle. Each resistor element is typically a pad of a resistivematerial and measures about 35 μm×35 μm. The printhead is held andprotected by an outer packaging referred to as a print cartridge or aninkjet pen. Upon energizing of a particular resistor element, a dropletof inkjet ink is expelled through the nozzle toward the print medium.The firing of ink droplets is typically under the control of amicroprocessor, the signals of which are conveyed by electrical tracesto the resistor elements, forming alphanumeric and other characters onthe print medium. The small scales of the nozzles, which are typically10 μm to 40 μm in diameter, require that the ink does not clog thenozzles. However, repeated firings of the resistor elements, which aredesigned to withstand millions of firings over the life of the printcartridge, result in fouling of the resistor elements with residue anddegradation of pen performance. This build up of residue is known askogation. The term “kogation” is, thus, used herein to refer to thebuildup of the residue, or koga, on a surface of the resistor element inthe inkjet pen.

To produce high quality images, the inkjet ink has to be compatible withthe inkjet pen and the print medium. In addition, the ink has to becapable of passing through the inkjet orifice without clogging theorifice plate.

Inkjet ink typically includes one or more colorants dissolved ordispersed in an aqueous-based ink vehicle and can also containanti-kogation components. Such anti-kogation components have been usedto counter the kogation effect. However, such components tend to be notstable in the ink composition and often precipitate. Such precipitationphenomenon results in a deposition phenomenon which tend clog the nozzleof the print head

Clogging of ink occurs when ink drops, exiting the orifices, leavebehind minute amounts of ink on the orifice plate around each orifice.The inkjet ink collects on an outer surface of the orifice plate orpuddles adjacent to the edge of the orifice. Such clogging happens atthe fore end of the narrow nozzle so that the direction and quantity ofink jetted become unstable. This clogging effect results in that thesize and the speed of ink drops vary exceedingly whereby it becomesimpossible to obtain a clear record and jet printing is hampered. Thisphenomena result thus in poor printing performances.

Clogging naturally happen on inks, however, this phenomenon isaccentuated by precipitation of some components of ink composition, suchas anti-kogation components, and furthermore, is accentuated when metalions contaminate ink composition.

It has thus often created challenges to formulate ink compositions whichdo not have a kogation effect and which do not result in clogging thenozzle of the printing machine; in other words, which can be effectivelyused with inkjet printing techniques and which provide good imageprinting performances.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the present disclosure, some embodimentswill be described below by way of non-limiting examples only, withreference to figures, wherein:

FIG. 1 is a graph representing drop weight (ng) versus milliondrops/nozzle (MDPN) of a control ink composition compared to an inkcomposition according to embodiment(s) of the present disclosure; and

FIG. 2 depicts 100× optical images of resistor surfaces after kogationtesting on a resistor life tester for a control ink composition and anink composition according to embodiment(s) of the present disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure will employ, unless otherwiseindicated, techniques of synthetic organic chemistry, ink chemistry,media chemistry, printing chemistry, and the like, that are within theskill of the art. Such techniques are explained fully in the literature.The following examples are put forth to provide those of ordinary skillin the art with a complete disclosure and description of how to performthe methods and use the compositions disclosed and claimed herein.Efforts have been made to ensure accuracy with respect to numbers (e.g.,amounts, temperature, etc.) but some errors and deviations should beaccounted for. Unless indicated otherwise, temperature is in ° C., andpressure is at or near atmospheric. Standard temperature and pressureare defined as 20° C. and 1 atmosphere. Unless indicated otherwise, theviscosity is expressed in cP and is measured at a temperature of 25° C.

Before embodiments of the present disclosure are described in detail, itis to be understood that, unless otherwise indicated, the presentdisclosure is not limited to particular materials, and processesdisclosed herein as such may vary to some degree. It is also to beunderstood that the terminology used herein is for purposes ofdescribing particular embodiments only, and is not intended to belimiting, as the scope of the present invention will be defined only bythe appended claims and equivalents thereof.

In the present specification, and in the appended claims, the followingterminology will be used: the singular forms “a”, “an”, and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a support” includes a plurality ofsupports. The terms “about” and “approximately,” when referring to anumerical value or range is intended to encompass the values resultingfrom experimental error that can occur when taking measurements.Concentrations, amounts, and other numerical data may be presentedherein in a range format. It is to be understood that such range formatis used merely for convenience and brevity and should be interpretedflexibly to include not only the numerical values explicitly recited asthe limits of the range, but also to include all the individualnumerical values or sub-ranges encompassed within that range as if eachnumerical value and sub-range is explicitly recited. For example, aweight range of about 1 weight percentage (wt %) to about 20 weightpercentage (wt %) should be interpreted to include not only theexplicitly recited concentration limits of 1 wt % to approximately 20 wt%, but also to include individual concentrations such as 2 wt %, 3 wt %,4 wt %, and sub-ranges such as 5 wt % to 15 wt %, 10 wt % to 20 wt %,etc.

As used herein, “images” refers to marks, signs, symbols, figures,indications, and/or appearances deposited upon a material or substratewith either visible or an invisible ink composition. Examples of animage can include characters, words, numbers, alpha-numeric symbols,punctuation, text, lines, underlines, highlights, and the like.

In some embodiments, the inkjet ink composition includes an inkjetvehicle, from about 0.1 to about 10 weight percentage of colorants, fromabout 0.01 to about 10 weight percentage of anti-kogation agents andfrom about 0.01 to about 10 weight percentage of a dispersed resinbeads.

In some embodiments, the ink composition is an inkjet ink printingcomposition. By inkjet composition, it is meant herein that thecomposition is very well adapted to be used in an inkjet device and inan inkjet printing process. In other words, the ink composition issuitable for inkjet ink printing.

It has likewise been observed that ink compositions often tend to sufferfrom kogation of resistors, resulting in shortened lifetime of theprinthead and decreased print quality at earlier stages in the life ofthe printhead. Anti-kogation elements have often been used to avoid suchkogation problems. However, inks containing such anti-kogation elementstend to suffer from clogging problems. Indeed, without being linked byany theory, it is believed that the anti-kogation elements react withmetal ions, and create insoluble salts that precipitate and load thefilters present in the printhead, and ultimately clog the flow of ink tothe nozzles.

In some embodiments, inkjet ink composition of the present disclosurereduces the clogging phenomenon that can happen in internal inkchannels, in firing chambers, or in nozzles of the printhead. Thecomposition of the present disclosure has a good affect on thefilterability of the ink (i.e., the ink can be easily filtered). Thisproperty reflects the anti-clogging effect of the ink composition.Small-mesh filters are used in the ink circulation system for preventingthe above mentioned clogging at the narrow nozzle portion. However, thisdesign encounters problem that the filters clog. Thus, by reducing theclogging effect, the composition of the present disclosure enhancestherefore the filterability of the ink composition. Thus, in someembodiments, the composition offers a means to avoid filterabilityissues and/or potential nozzle clogging issues.

In some embodiments, the presence of anti-kogation agents and watersoluble components, such as disclosed herein, reduces the amount ofmultivalent metal ion (such as calcium) presents in ink composition.Without being bound by any theory, it is believed that the efficiency ofcomponents to bind calcium reflects the anti-clogging effect and thefilterability characteristics of ink compositions.

In addition, the composition of the present disclosure presents improvedprinting characteristics. Indeed, kogation and clogging problems tend toreduce drop velocity and drop weight and tend to reduce the efficiencyof drop ejection. A loss of drop weight over the life of the inkjet penreduces the color saturation or optical density of the inkjet ink on theprint medium and, therefore, degrades print quality. Furthermore, a lossof drop weight over the life of the inkjet pen reduces the accuracy ofdrop placement on the print medium and, therefore, degrades printquality. Thus, by reducing the kogation and clogging phenomenon, thecomposition disclosed herein has improved printing characteristics.Thus, as examples, the ink composition improves drop velocity, and asother examples, improves efficiency of drop ejection.

In some embodiments, the present disclosure relates to method ofprolonging the service life of an inkjet print head, to be used for aninkjet recording method, including discharging ink from an orificewherein the ink contains: an inkjet vehicle, from about 0.1 to about 10weight percentage of colorants, from about 0.01 to about 10 weightpercentage of anti-kogation agents and from about 0.01 to about 10weight percentage of resin beads.

In some embodiments, the pH of the ink composition may be varied asdesired. In some embodiments, the pH of the ink ranges from about 3 toabout 11, depending upon the type of colorant being used. In an example,the pH of the present ink is from about 5 to about 9 and, in anotherexample, from about 5.5 to about 7.5. The pH of the ink compositions maybe adjusted by the addition of organic or inorganic acids or bases,i.e., pH adjusting agent. Typical pH adjusting agent includes inorganicacids such as hydrochloric, phosphoric and sulfuric acids. Typicalorganic acids include methane sulfonic, acetic and lactic acids. Typicalinorganic bases include alkali metal hydroxides and carbonates. In someembodiments, pH adjusting agent is ammonium hydroxide. Any suitableamount of the pH adjusting agent can be used. In an example, the pHadjusting agent is used in an amount of from about 0.1 to about 1percentage by weight, and, in another example, in an amount of fromabout 0.3 to about 0.7 percentage by weight of the composition.

In some embodiments, the ink compositions have a viscosity within therange of about 1.0 to about 10 cps, and, in other embodiments, of about1.0 to about 7.0 cps, as measured at 25° C., in order to achieve thedesired rheological characteristics. As indicated above, the viscosityof the ink composition is conveniently regulated, as known to those ofordinary skill in the art, for instance, by suitable choice of thequantity and the molecular weight of the binders resin, the organicsolvent, the wax, and other agents.

In some embodiments, the ink composition includes resin beads. In anexample, the resin beads are dispersed into the liquid vehicle of theink composition.

In some embodiments, the resin beads are present in an amountrepresenting from about 0.01 to about 10 weight percentage. In someother examples, the resin beads are present in an amount representingfrom about 0.10 to about 10 weight percentage by total weight of the inkcomposition and, in other examples, in an amount representing from about0.20 to about 2 weight percentage by total weight of the ink composition

During the inkjet process, due to their specific size, the beads willstay on the printhead, meaning thus that they are not going to beejected via the nozzle and they will not be ejected onto the substrate.As an example, the beads would stay behind filter in the ink supply orin pen body or in the ink supply container. In some examples, the inkflows through the filter to the firing chamber whereas the beads, havinga size unable to pass through the filter, stay behind.

Thus, in some embodiments, the size of the beads is bigger than the poresize of the filter present in the pen's ink delivery system. Thus, insome embodiments, the beads have a size of at least 1 μm in diameter. Inother embodiments, the resin beads have a size ranging from about 5 toabout 800 μm in diameter; in some other embodiments, the resin beadshave a size ranging from about 50 to about 600 μm in diameter. In yetother embodiments, the resin beads have a size ranging from about 450 toabout 550 μm in diameter.

As used herein, the term beads refers to any spherical or irregularshaped particles that are dispersed in the ink composition and that havethe capacity of interfering and trapping ions materials. As an example,the beads are water dispersible. In some embodiments, the beads areion-exchange resins and have the capacity of interfering and trappingionic materials, and especially, multivalent metal ion materials.

In some embodiments, the resin beads include an organic or an inorganicpolymer and a functional group. In some examples, the resin beadscontains, as a functional group, any groups that would bind multivalentmetal ions. Thus, in some embodiments, the resin beads are ion-exchangeresin beads.

In some embodiments, the functional group can be any entity including adi-acid groups, or any homologues of ethylenediamine with acetic acid orany substituted methylphosphonic acid. In some other embodiments, resinbeads contain, as functional group, a compound selected from the groupconsisting of iminodiacetic acid and imino-diacetate.

In some other embodiments, resin beads contain a functional groupselected from the group consisting of iminodiacetic acid group (IDA) oraminomethylphosphonic acid (AMPA) group ordiethylenetriaminetetraacetate (TAAcOH) group.

In some embodiments, the resins are organic polymers or inorganicpolymers. As an example, the resins are based on cross-linkedpolystyrene. In some embodiments, the resins encompass high molecularcomposition-made matrixes. Such high molecular composition-made matrixesare of the phenol type, styrene type, acryl type, acrylic acid-type andpyridine-type. In some other embodiments, the resins are syntheticresins such as: polyamide, unsaturated polyester, polyurethane, epoxy,silicone or copolymer of an unsatured dicarboxylic acid and styrene. Asan example, the resins containing the functional group are polystyrenecross-linked with divinylbenzene.

In some other examples, the polymer, constituting the resin, is aninorganic polymer such as precipitated silica. As another example, theresin beads are precipitated silica with triamine-tetra-acetic acidsurface modification or salt thereof.

Examples of resin beads include, but are not limited to, beads that arecommercially available under the tradename QuadraPure® (available fromReaxa Corp.) or under the tradename SiliaBond® (available from SilicycleInc.).

In some embodiments, the inkjet ink composition includes anti-kogationagents. As anti-kogation agent, it is meant herein any components thatprevent or reduce the kogation effect. The anti-kogation agent used inthe ink composition may be an anionic surfactant, a nonionic surfactant,a zwitterionic surfactant, an amphoteric surfactant, or mixturesthereof.

As used herein, the term “amphoteric surfactant” refers to a surfactantthat includes both cationic groups and anionic groups. If the amphotericsurfactant is present in an acidic environment, the amphotericsurfactant has cationic groups, while the amphoteric surfactant hasanionic groups in a basic environment. At isoelectric point (IEP), theamphoteric surfactant has an overall neutral charge because bothcationic groups and anionic groups are present.

As used herein, the term “zwitterionic surfactant” refers to asurfactant that includes both anionic groups and cationic groups and,therefore, has a neutral charge. The zwitterionic surfactant differsfrom the amphoteric surfactant in that the charge on the zwitterionicsurfactant is not as sensitive to changes in pH.

In some embodiments, the anti-kogation agent is an anionic surfactant.In other embodiments, the anti-kogation agent has a neutral charge. Assuch, the anti-kogation agent may be nonionic, amphoteric, orzwitterionic. In some embodiments, the ink composition has a neutral pHso that the anti-kogation agent has an overall neutral charge. In someembodiments, the anti-kogation agent is a phosphate-containingsurfactant, such as a phosphate ester surfactant. Examples of phosphateester surfactants include, but are not limited to, surfactants that arecommercially available under the tradename Emphos®, DeSophoS®,Hostaphat®, ESI-Terge®, Emulgen®, Crodafos®, Dephotrope®, and DePhOS®,which are available from Witco Corp. (Middlebury, Conn.), Clariant GmbH(Frankfurt, Germany), Cook Composites and Polymers Co., (Kansas City,Mo.), Kao Specialties Americas LLC (High Point, Nalco), Croda Inc.(Parsippany, N.J.), DeForest Enterprises, Inc. (Boca Raton, Fla.), andDeForest Enterprises, Inc. (Boca Raton, Fla.), respectively. Specificexamples of phosphate ester surfactants that may be used include, butare not limited to, Crodafos®N-3 Acid, Emphos®9NP, Emphos®CS121,Emphos®CS131, Emphos®CS141, Emphos®CS1361, Hostaphat®LPKN,ESI-Terge®320, ESI-Terge®330, DePhoS®8028, Emulgen®BL-2PK, DeSophos®4P,DeSophoS®6 MPNa, DeSophoS®8DNP, DeSophoS®9NP, DeSophoS®30NP orDephotrope®CAS-MF. In addition, mixtures of these phosphate estersurfactants may be used.

In some embodiments of the present disclosure, the inkjet inkcomposition includes a phosphate-containing surfactant as anti-kogationagent. In some other embodiments, the anti-kogation agent is a phosphateester surfactant. In yet some other embodiments, the anti-kogation agentis a phosphate ester of a fatty alcohol alkoxylate surfactant. In someembodiments, the phosphate ester of a fatty alcohol alkoxylate is amixture of mono- and di-esters. In other embodiments, the phosphateester of a fatty alcohol alkoxylate has an acid number ranging from 50to 150. In some embodiments, the anti-kogation agent is an ethoxylatedmono-oleyl phosphate ester.

The anti-kogation agent may be oleth-3 phosphate, a nonylphenolethoxylate phosphate ester, a salt of a nonylphenol ethoxylate phosphateester, an organo-phosphate, an aliphatic phosphate ester, a phosphatednonylphenoxy polyethoxy ethanol, or a salt of ethyl-hexanol ethoxylatedphosphate ester (2EH-2EO). In other embodiments, the anti-kogation agentis selected from the group consisting of oleth-3 phosphate, oleth-10phosphate, oleth-5 phosphate, dioleyl phosphate, ppg-5-ceteth-10phosphate, C₉-C₁₅ alkyl monophosphate, deceth-4 phosphate, and mixturesthereof.

In other embodiments, the inkjet ink composition includes, asanti-kogation agent, a compound having the formula (II) below, wherein nis from 0 to 15.

Examples of anti-kogation agent include surfactants of theCrodafos®family available from Croda Inc such as Crodafos®N3A,Crodafos®N3E, Crodafos®N10A, Crodafos®HCE and Crodafos®SG. Otherexamples of the phosphate-containing surfactants include Arlatone®Map950 available from Croda Inc; Monofax® 831, Monofax®1214 available fromMona Industries; Monalube® 215 and Atlox®DP13/6 available from CrodaInc.

In some embodiments, the anti-kogation agent is present in an amountrepresenting from about 0.01 to about 10 percentage by weight (wt %) oftotal weight of the ink composition. In some examples, the anti-kogationagent is present in an amount representing from about 0.2 to about 3weight percentage. In other examples, the anti-kogation agent is presentin an amount representing from about 0.4 to about 1 weight percentage ofthe total weight of the ink composition.

The ink composition includes one or more colorants that impart thedesired color to the printed message. As used herein, “colorant”includes dyes, pigments, and/or other particulates that may be suspendedor dissolved in an ink vehicle.

The colorant system is present in an amount representing from about 0.1to about 10 percentage by weight (wt %), in some examples, in an amountrepresenting from about 1 to about 6 percentage by weight, and in otherexamples, in an amount representing from about 1 to about 4 percentageby weight of the ink composition. The colorant is generally present inan amount required to produce the desired contrast and readability.

In some embodiments, according to the present disclosure, the inkincludes pigments as colorants. As used herein, “pigment” refers to acolorant particle that is substantially insoluble in the liquid vehiclein which it is used. Pigments can be dispersed using a separatedispersing agent, or can be self-dispersed, having a dispersing agentattached to the surface of the pigment.

As used herein, “self-dispersed” generally refers to pigments that havebeen functionalized with a dispersing agent, such as by chemicalattachment of the dispersing agent to the surface of the pigment. Thedispersing agent can be a small molecule or a polymer or oligomer. Thedispersing agent can be attached to such pigments to terminate the outershell of the pigment with a charge, thereby creating a repulsive naturethat reduces agglomeration of pigment particles within the liquidvehicle. Another way to disperse carbon black is to surface treat thecarbon (with ozone, as an example) to create charged functional groupson the surface of the carbon itself.

The pigments that can be used in accordance with embodiments of thepresent disclosure include both self-dispersed pigments as well asdispersed pigments, e.g., pigments dispersed by a separate dispersingagent that is not covalently attached to the surface. If self-dispersed,a dispersant is typically prepared in a precursor form, and then theprecursor is attached to the pigment to chemically modify the surface ofthe pigment. In some embodiments, the dispersant can be attached to thepigment using various precursor materials, such as para-aminobenzoicacids, isophthalic acids, tricarboxylic acids, carboxylic groups,sulfonylic groups, phosphates, oligomers, polymers, and isomers thereof,for example.

As alluded to, pigment colorant can be used in accordance withembodiments of the present disclosure. Specifically, if black is used,the black pigment can be any commercially available black pigment thatprovides acceptable optical density and print characteristics. Suchblack pigments can be manufactured by a variety of known methods such aschannel methods, contact methods, furnace methods, acetylene methods, orthermal methods, and are commercially available from such vendors asCabot Corporation, Columbian Chemicals Company, Evonik, Mitsubishi, andE.I. DuPont de Nemours and Company. For example, commercially availablecarbon black pigments include Color Black FW 200, Color Black FW 2V,Color Black FW1, Color Black FW 18, Color Black FW S160, Color Black FWS170, Printex including 95, 85, 75, 55, 45, 300, 35, 25, 200, 12, andSpecial Blacks including, 4A, 4, 5, 6, 550, 350, 250; BP1100, BP900,BP800, M1100, M900, M800, Monarch 1400, Monarch 1300, Monarch 1000,Monarch 900, Monarch 880, and Monarch 700; Cab-O-Jet 200 and Cab-O-Jet300; Raven 2500ultra, Raven 2000, Raven 7000, Raven 5750, Raven 5250,Raven 5000, and Raven 3500; 45 B, and combinations thereof.

In addition to black, other pigment colorants can be used, such as cyan,magenta, yellow, blue, orange, green, pink, etc. Suitable organicpigments include, for example, azo pigments including diazo pigments andmonoazo pigments, polycyclic pigments (e.g., phthalocyanine pigmentssuch as phthalocyanine blues and phthalocyanine greens, perylenepigments, perynone pigments, anthraquinone pigments, quinacridonepigments, dioxazine pigments, thioindigo pigments, isoindolinonepigments, pyranthrone pigments, and quinophthalone pigments), insolubledye chelates (e.g., basic dye type chelates and acidic dye typechelate), nitropigments, nitroso pigments, anthanthrone pigments such asPR168, and the like. Representative examples of phthalocyanine blues andgreens include copper phthalocyanine blue, copper phthalocyanine greenand derivatives thereof (Pigment Blue 15 and Pigment Green 36).Representative examples of quinacridones include Pigment Orange 48,Pigment Orange 49, Pigment Red 122, Pigment Red 192, Pigment Red 202,Pigment Red 206, Pigment Red 209, Pigment Violet 19 and Pigment Violet42. Representative examples of anthraquinones include Pigment Red 43,Pigment Red 194, Pigment Red 177, Pigment Red 216 and Pigment Red 226.Representative examples of perylenes include Pigment Red 123, PigmentRed 190, Pigment Red 189 and Pigment Red 224. Representative examples ofthioindigoids include Pigment Red 86, Pigment Red 87, Pigment Red 198,Pigment Violet 36, and Pigment Violet 38. Representative examples ofheterocyclic yellows include Pigment Yellow 1, Pigment Yellow 12,Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow73, Pigment Yellow 90, Pigment Yellow 110, Pigment Yellow 117, PigmentYellow 120, Pigment Yellow 128, Pigment Yellow 138, Pigment Yellow 150,Pigment Yellow 151, Pigment Yellow 155, and Pigment Yellow 213. Suchpigments are commercially available in powder, press cake, or dispersionform from a number of sources.

The pigments of the present disclosure can be from about 5 nm to about10 μm in size; in another example, the pigments can be from 10 nm toabout 500 nm in size, although sizes outside this range can be used ifthe pigment can remain dispersed and provide adequate printingproperties.

In some embodiments, the inks can include dyes as colorants. Examples ofdyes suitable for use in the preparation of the ink composition include,but are not limited to, the yellow dyes such as C.I. Yellow 19 (C.I.13900A), C.I. Yellow 21 (C.I. 18690), C.I. Yellow 61, C.I. Yellow 80,FD&C Yellow #5, and the like, the orange dyes such as C.I. Orange 1(C.I. 11920), C.I. Orange 37, and the like, red dyes such as C.I.Solvent Red 8, C.I. Red 81, C.I. Solvent Red 82, and the like, pink dyessuch as Diaresin Pink M (Mitsubishi Chemical Industries, Ltd.), and thelike, violet dyes such as C.I. Solvent Violet 8, and the like, blue dyessuch as C.I. Solvent Blue 2, C.I. Solvent Blue 11, and the like, blackdyes such as C.I. Solvent Black 3, Acid Black 123, and the like. Some ofthe pigments and dyes are commercially available in convenientdispersions and may be used in the preparation of the ink compositionaccording to embodiments of the present disclosure. In some embodiments,the ink includes a mixture of dyes and pigments as colorants.

As used herein, “liquid vehicle” is defined to include any liquidcomposition that is used to carry colorants, including pigments, to asubstrate. A wide variety of liquid vehicle components may be used inaccordance with embodiments of the present disclosure. Such liquidvehicle may include a mixture of a variety of different agents,including without limitation, other surfactants, solvent andco-solvents, buffers, biocides, viscosity modifiers and water. In someembodiments, the liquid vehicle is an inkjet liquid vehicle.

In some embodiments, organic solvents are part of the liquid vehicles.Organic solvents are typically used to increase the solubility or thedispersibility of the resin or of the colorant that might be present inthe composition. Any suitable organic solvent can be used. Examples ofsuitable classes of organic solvents include the polar solvents such asamides, esters, ketones, lactones and ethers. Examples of suitableorganic solvents include N-methylpyrrolidone (NMP), dimethyl sulfoxide,sulfolane, and glycol ethers. In some embodiments, the solvent is2-pyrrolidone or a derivative of 2-pyrrolidone, such as 1-(2hydroxyethyl)-2-pyrrolidone. In some other embodiments, the liquidvehicle includes a plurality of solvents.

As an example, the solvent is used in an amount representing from about0.1 to about 30 weight percentage of the ink composition and; in otherembodiments, in an amount of from about 8 to about 25 weight percentageof the ink composition.

In some embodiments, the ink composition includes water. In someembodiments, water is used as the ink carrier for the composition and ispart of the liquid vehicle. Generally, the water makes up the balance ofthe ink composition, and may be present in an amount representing fromabout 40 to about 90 weight percentage, in some embodiments representingfrom about 50 to about 80 weight percentage by weight of the totalcomposition. In order to prevent the clogging of inkjet tip by dissolvedsalts in the water, deionized water may be used in the preparation ofthe ink composition.

In addition to water, various types of agents may be employed in the inkcomposition to optimize the properties of the ink composition forspecific applications. For example, the ink composition may also includeany number of buffering agents and/or biocides. Any number of commonlyknown buffers may be used to establish a desired pH level in the inksystem. Additionally, in some embodiments, various biocides are used toinhibit growth of undesirable microorganisms. Several examples ofsuitable biocides include, but are in no way limited to, benzoate salts,sorbate salts, commercial products such as Nuosept® (ISP), Ucarcide®(Dow), Vancide® (RT Vanderbilt Co.), and Proxel® (Avecia), Kordek® MLX(Rohm and Haas) and other known biocides. Such biocides may be comprisedin amount representing less than about 5 weight percentage of the inkcomposition. In some examples, biocides represents from about 0.05 toabout 2 weight percentage of the ink composition.

In further detail with respect to the surfactant, the inkjet inkcompositions can be substantially free of surfactant other than thephosphate-containing surfactant of the anti-kogation agent. However,certain second surfactants can also be used and may include standardwater-soluble surfactants such as alkyl polyethylene oxides, alkylphenyl polyethylene oxides, polyethylene oxide (PEO) block copolymers,acetylenic PEO, PEO esters, PEO amines, PEO amides, dimethiconecopolyols, ethoxylated surfactants, fluorosurfactants, and mixturesthereof. In one example, a fluorosurfactant can be used as the secondsurfactant. In other examples, a secondary alcohol ethoxylatedsurfactant can be used. If used, the second surfactant can be present atfrom about 0.001 to about 10 weight percentage, and, in other examples,can be present at from about 0.001 to about 0.1 weight percentage of theinkjet ink composition.

In some embodiments, the ink composition can contain latexes. Latexesinclude both latex particulates as well as the aqueous medium in whichthe latex particulates are dispersed. Latex is a liquid suspensionincluding a liquid (such as water and/or other liquids) and polymericparticulates from about 20 nm to about 500 nm in size. As an example,the polymeric particulate can be present in the liquid at from about 0.5to about 20 weight percentage. Such polymeric particulates can include aplurality of monomers that are typically randomly polymerized, and canbe crosslinked.

Any latex polymer commercially available can be used in the inks of thepresent disclosure including self-dispersed and functionalized latexpolymers. Latex polymers can be prepared using any of a number of knownemulsion polymerization techniques where co-monomers are dispersed andpolymerized in a discontinuous phase of an emulsion. Monomers that areoften used include ethyl acrylate; ethyl methacrylate; benzyl acrylate;benzyl methacrylate; propyl acrylate; propyl methacrylate; iso-propylacrylate; iso-propyl methacrylate; butyl acrylate; butyl methacrylate;hexyl acrylate; hexyl methacrylate; octadecyl methacrylate; octadecylacrylate; lauryl methacrylate; lauryl acrylate; hydroxyethyl acrylate;hydroxyethyl methacrylate; hydroxyhexyl acrylate; hydroxyhexylmethacrylate; hydroxyoctadecyl acrylate; hydroxyoctadecyl methacrylate;hydroxylauryl methacrylate; hydroxylauryl acrylate; phenethyl acrylate;phenethyl methacrylate; 6-phenylhexyl acrylate; 6-phenylhexylmethacrylate; phenyllauryl acrylate; phenyllauryl methacrylate;3-nitrophenyl-6-hexyl methacrylate; 3-nitrophenyl-18-octadecyl acrylate;ethyleneglycol dicyclopentyl ether acrylate; vinyl ethyl ketone; vinylpropyl ketone; vinyl hexyl ketone; vinyl octyl ketone; vinyl butylketone; cyclohexyl acrylate; methoxysilane;acryloxypropyhiethyl-dimethoxysilane; trifluoromethyl styrene;trifluoromethyl acrylate; trifluoromethyl methacrylate;tetrafluoropropyl acrylate; tetrafluoropropyl methacrylate;heptafluorobutyl methacrylate; iso-butyl acrylate; iso-butylmethacrylate; 2-ethylhexyl acrylate; 2-ethylhexyl methacrylate;iso-octyl acrylate; and iso-octyl methacrylate.

As an example, the ink composition of the present disclosure can be usedin a method of forming printed images on surfaces in a heatedenvironment. The method includes projecting a stream of droplets of theink composition onto a surface to form the desired printed image. Theinkjet ink composition may be established on the substrate via anysuitable inkjet printing techniques. Non-limitative examples of suchinkjet printing techniques include thermal, acoustic, and piezoelectricinkjet printing. In some embodiments, the inks are utilized in thermalinkjet printers. An example of method of prolonging the service life ofthe inkjet print head includes discharging ink from an orifice onto amedia substrate wherein the ink contains an inkjet vehicle, from about0.1 to about 10 weight percentage of colorants, from about 0.01 to about10 weight percentage of anti-kogation agents, and from about 0.01 toabout 10 weight percentage of dispersed resin beads.

Another example of method of inkjet printing over a prolonged period oftime, includes jetting an inkjet ink onto a media substrate, wherein theinkjet ink includes: an inkjet vehicle, from about 0.1 to about 10weight percentage of colorants, from about 0.01 to about 10 weightpercentage of anti-kogation agent having the formula (II) wherein n isfrom 0 to 15:

and from about 0.01 to about 10 weight percentage of dispersed resinbeads including an organic polymer or an inorganic polymer and afunctional group selected from the group consisting of iminodiaceticacid group (IDA) or aminomethylphosphonic acid (AMPA) group ordiethylenetriaminetetraacetate (TAAcOH) group.

The introduction of a combination of anti-kogation agents and resinbeads, such as disclosed herein, reduces the kogation phenomenon ofresistors and, in addition, ameliorates or even substantially eliminatesclogging phenomenon that can happen in internal ink channels, in firingchambers, or in nozzles of the printhead. Examples of ink compositionsextend thus the life of inkjet pens in general (and particularly thermalinkjet pens) which carry such inks.

The images are printed on porous and non-porous surfaces, in someembodiments on porous surfaces, using the ink composition of embodimentsof the present disclosure. In other embodiments, the substrate is paper(non-limitative examples of which include plain copy paper or papershaving recycled fibers therein) or photo-paper (non-limitative examplesof which include polyethylene or polypropylene extruded on one or bothsides of paper), and/or combinations thereof. In some embodiments, thesubstrate has a thickness along substantially the entire length rangingbetween about 0.025 mm and about 0.5 mm. In some embodiments, theprinted surface can be any plastic coated media (as used in out-doorsignage) and tracing media (for architectural drawings).

As used herein, “images” refers to marks, signs, symbols, figures,indications, and/or appearances deposited upon a substrate with eithervisible or an invisible ink composition. Examples of an image caninclude characters, words, numbers, alpha-numeric symbols, punctuation,text, lines, underlines, highlights, and the like.

In other embodiments, the inks are utilized in an inkjet set including,at least, magenta, cyan, yellow and black inks. Colorless inkcompositions that contain non-colored particles and no colorant may alsobe used.

The following examples illustrate the embodiments of the disclosure thatare presently best known. However, it is to be understood that thefollowing are only exemplary or illustrative of the application of theprinciples of the present invention. Numerous modifications andalternative compositions, methods, and systems may be devised by thoseskilled in the art without departing from the spirit and scope of thepresent invention. The appended claims are intended to cover suchmodifications and arrangements. Thus, while the present invention hasbeen described above with particularity, the following examples providefurther details in connection with what are presently deemed to be themost practical and preferred embodiments of the invention.

Example 1 Ink Formulations

Ink compositions are prepared in accordance with Table A as follows. Allnumbers represent the weight percentage of each component by totalweight of the ink composition. Ink formulations B, C, D and E arecomparative inks.

TABLE A Formulations A B C D E 1-(2 hydroxy- 8.00 8.00 8.00 8.00 8.00ethyl)- 2-pyrrolidone 2-pyrrolidone 7.00 7.00 7.00 7.00 7.001,6-Hexanediol 3.00 3.00 3.00 3.00 3.00 Tetraethylene 3.00 3.00 3.003.00 3.00 Glycol Liponic ® EG-1 2.00 2.00 2.00 2.00 2.00 Surfynol ® SEF1.10 1.10 1.10 1.10 1.10 Crodafos ® N-3 1.00 1.00 1.00 1.00 — Proxel ®GXL 0.10 0.10 0.10 0.10 0.10 Kordek ® MLX 0.14 0.14 0.14 0.14 0.14Joncryl ® 683 0.20 0.20 0.20 0.20 0.20 (K salt) QuadraPure ® 0.75 — 9.20— 6.70 IDA Colorant 3.00 3.00 3.00 3.00 3.00 Water Up Up Up Up Up to 100to 100 to 100 to 100 to 100 Extra Ca²⁺ — —  0.0006   0.00005 —

Surfynol® SEF is a surfactant available from Air Products. Joncryl® 683is an acrylic resin available from BASF. Proxel® GXL is a Biocideavailable from Zeneca. Crodafos® N-3 acid is available from Croda Inc.Liponic® EG-1 is a surfactant available from Dow Corning. Kordek® MLX isa biocide available from Rohm and Haas. QuadraPure® IDA are resin beadsavailable from Reaxa Corp.

Example 2 Kogation Performance of Ink Composition

Ink compositions are evaluated for their efficacy in reducing kogation.Inkjet inks formulation A and E are loaded into two different thermalinkjet architectures and fired initially for baseline readings relatedto steady state drop weight. Each ink composition is printed through itsrespective print architecture at 400 million drops per nozzle. Thenozzle size for this particular study is about 20 microns. The kogationperformance is determined by measuring the drop weight retained aftersignificant volume of ink firing. The kogation test is carried out withmultiple repeating pens for average results. The drop weight, expressedin nanograms (ng), is determined for the ink compositions A and E at 0,1, 10, 50, 100, and 200 million drops/nozzle (MDPN). The results areillustrated in FIG. 1.

As shown in FIG. 1, the control composition E shows poor or marginalkogation performances. A significant decrease in the drop weight isobserved over the course of firing 10 million drops/nozzle. On theopposite, ink composition A shows good kogation performances.

In addition, after printing, the resistor surfaces are visuallyinspected with an optical microscope to determine whether kogation ispresent. 100× optical image of resistor surfaces is determined for theink compositions A and E after 400 million drops/nozzle. The results areillustrated in FIG. 2. FIG. 2 shows 100× optical images of resistorsurfaces for ink compositions A and E after kogation testing on theresistor life tester. FIG. 2 demonstrates that the resistor surface ofcomposition A is cleaner compared to that observed with the inkcomposition E, i.e., there is no deposit on the surface of the resistor.This means thus that composition E shows poor kogation performanceswhile ink composition A shows a significant improvement in the kogationperformances.

Example 3 Calcium Binding Capacities

Compositions are evaluated herein for their capacity in binding metalsions. The efficiency to bind calcium reflects the anti-clogging effectof the ink components.

Compositions including resin beads and different anti-kogation agents(Crodafos® N3, Crodafos® N10 available from Croda Inc.) are stirred witha 20 ppm solution of calcium in deionized water. Anti-kogation agents(Crodafos® N3 or Crodafos® N10) are added to the calcium solution beforethe addition of resin beads. The samples are stirred at room temperatureover the weekend, filtered and submitted for ICP-OES analysis(Inductively coupled plasma—Optical Emission Spectroscopy). The contentof calcium present in each solution is then evaluated. The results aresummarized in Table B below. The quantity of calcium is expressed inparts per million (ppm) and represents the amount of calcium detected in20 ppm of solution.

TABLE B Compositions Calcium content 25 g Calcium Solution, 1.6 10 mgQuadraPure ®IDA 25 g Calcium Solution, 1.5 10 mg QuadraPure ®AMPA 25 gCalcium Solution, 20 10 mg PL-MeMal ® 10 g Calcium Solution, 3.2 0.1 gCrodafos ® N3 25 g Calcium Solution, 2.6 0.25 g Crodafos ® N3, 10 mgQuadraPure ®IDA 25 g Calcium Solution, 2.4 0.25 g Crodafos ® N3, 10 mgQuadraPure ®AMPA 10 g Calcium Solution, 20 0.1 g Crodafos ® N10 25 gCalcium Solution, 2.7 0.25 g Crodafos ® N10, 10 mg QuadraPure ®IDA 25 gCalcium Solution, 3.5 0.25 g Crodafos ® N 10, 10 mg QuadraPure ®AMPACalcium Solution 16 verification limit 1.0

QuadraPure®AMPA is resin bead available from Reaxa. QuadraPure®IDA isresin beads available from Reaxa. PL-MeMal® are resin beads availablefrom the Polymer Labs division of Varian Inc. Crodafos® N3 and Crodafos®N10 are available from Croda Inc.

These results demonstrate that resin beads containing iminodiacetic acidgroup (IDA) or AMPA aminomethylphosphonic acid group (AMPA) asfunctional group have good capacity for binding metal ions. Theseresults demonstrate also that some resin beads combined with someanti-kogation agents exhibit good capacity for binding metal ions.

Example 4 Filterability Performances of Ink Compositions

Formulations of Table A are analyzed for their filterabilityperformances. Such filterability performances represent theanti-clogging benefit of the ink compositions, i.e., the ability of notclogging the nozzles and/or the filters of the printhead. The additionof calcium reflects the inclination of anti-kogation agents toprecipitate and the tendency of the inks containing them to clog filtersand printhead nozzles. The filtration of each ink is evaluated byputting 15 g of each ink through a 1 μm pore size filter. The ink isfirst spiked with a metal-salt solution (Ca²⁺); the ink is agitated for2 weeks and is then evaluated. The results are summarized in Table C.

In Table C, the filterability time corresponds to the tendency of ink toclog. The lower the filter time is, the better the anti-clogging effectis. The time taken to filter the given sample is thus an indication ofthe ink's anti-clogging performance.

TABLE C Ink Ca Resin Time to filter the ink formu- spike beads (insecond or in minute) lation (ppm) (grams) Run #1 Run #2 Run #3 B 0 0 13sec 14 sec 13 sec A 0 0.115 12 sec 13 sec 13 sec D 5 0 5 min/9 mL 5min/8.5 mL N/A C 60 1.375 12 sec 11 sec 11 sec

As demonstrated herein, the presence of a combination of anti-kogationagents and of resin beads in ink composition clearly reduces the amountof metal (calcium) present in the ink formulation. The resultsdemonstrate that inks containing such combination of anti-kogationagents and of resin beads results in ink compositions that have a lowtime to filter, meaning thus that such combination does not presentclogging effect.

The preceding description has been presented only to illustrate anddescribe exemplary embodiments of the present invention. Althoughcertain example methods, compositions, apparatus and articles ofmanufacture have been described herein, the scope of coverage of thispatent is not limited thereto. On the contrary, this patent covers allmethods, apparatus and articles of manufacture fairly falling within thescope of the claims either literally or under the doctrine ofequivalents.

1) An inkjet ink composition comprising: a. an inkjet vehicle, b. fromabout 0.1 to about 10 weight percentage of colorants, c. from about 0.01to about 10 weight percentage of anti-kogation agents, d. and from about0.01 to about 10 weight percentage of dispersed resin beads. 2) Theinkjet ink according to claim 1 wherein the dispersed resin beads have asize of at least 1 μm in diameter. 3) The inkjet ink according to claim1 wherein the dispersed resin beads have a size ranging from about 5 toabout 800 μm in diameter. 4) The inkjet ink according to claim 1 whereinthe dispersed resin beads comprise an organic polymer or an inorganicpolymer and a functional group. 5) The inkjet ink according to claim 1wherein the dispersed resin beads contain a functional group selectedfrom the group consisting of iminodiacetic acid group (IDA),aminomethylphosphonic acid (AMPA) group ordiethylenetriaminetetraacetate (TAAcOH) group. 6) The inkjet inkaccording to claim 1 wherein the anti-kogation agent is aphosphate-containing surfactant. 7) The inkjet ink according to claim 1wherein the anti-kogation agent is a phosphate ester surfactant. 8) Theinkjet ink according to claim 1 wherein the anti-kogation agent is aphosphate ester of a fatty alcohol alkoxylate surfactant. 9) The inkjetink according to claim 1 wherein the anti-kogation agent is anethoxylated mono-oleyl phosphate ester surfactant. 10) The inkjet inkaccording to claim 1 wherein the anti-kogation agent is selected fromthe group consisting of oleth-3 phosphate, oleth-10 phosphate, oleth-5phosphate, dioleyl phosphate, ppg-5-ceteth-10 phosphate, C₉-C₁₅ alkylmonophosphate, deceth-4 phosphate, and mixtures thereof. 11) The inkjetink according to claim 1 wherein the anti-kogation agent has the formula(II) wherein n is from 0 to 15:

12) The inkjet ink of claim 1, wherein the anti-kogation agent ispresent in an amount representing from about 0.2 to about 3 weightpercentage by weight of the ink composition. 13) The inkjet inkaccording to claim 1 wherein the colorant is a pigment. 14) A method ofinkjet printing over a prolonged period of time, comprising jetting aninkjet ink onto a media substrate, wherein said inkjet ink includes: a.an inkjet vehicle, b. from about 0.1 to about 10 weight percentage ofcolorants, c. from about 0.01 to about 10 weight percentage ofanti-kogation agents, d. and from about 0.01 to about 10 weightpercentage of dispersed resin beads. 15) The method of inkjet printingover a prolonged period of time, according to claim 14, wherein saidinkjet ink includes: a. an inkjet vehicle, b. from about 0.1 to about 10weight percentage of colorants, c. from about 0.01 to about 10 weightpercentage of an anti-kogation agent having the formula (II) wherein nis from 0 to 15:

d. and from about 0.01 to about 10 weight percentage of dispersed resinbeads comprising an organic polymer or an inorganic polymer and afunctional group selected from the group consisting of iminodiaceticacid group (IDA), aminomethylphosphonic acid (AMPA) group ordiethylenetriaminetetraacetate (TAAcOH) group.